On Sun, Jun 04, 2023 at 02:17:16PM +0200, Johan Hovold wrote: > On Fri, Jun 02, 2023 at 11:46:56AM -0500, Corey Minyard wrote: > > On Fri, Jun 02, 2023 at 02:53:31PM +0200, Johan Hovold wrote: > > > > I just posted a patch series which does that. The USB serial drivers do > > > not currently return any errors related to break signalling even though > > > this has been possible since 2008. > > > > > > The same mechanism can be used to report that break signalling is not > > > supported by a device or driver, but the USB serial drivers would be the > > > first tty drivers that actually do this. If it turns out to cause any > > > trouble we can still use this series to avoid the unnecessary wait. > > > > > > Care to give the series a try? > > > > > > https://lore.kernel.org/lkml/20230602124642.19076-1-johan@xxxxxxxxxx > > > > I have tested this series. I can verify that one of the CP2105 ports > > (ttyUSB0) does not return an error on sending the break, and the other > > (ttyUSB1) does. This is the only USB serial device on the system. > > Thanks for testing. > > > However, the device hooked to the remote console (ttyUSB0), the one not > > returning an error on sending a break, still doesn't send a break. So > > my problem isn't fixed :-(. > > > > # ls -l /dev/serial/by-path > > total 0 > > lrwxrwxrwx 1 root root 13 Jun 2 15:28 pci-0000:00:1d.0-usb-0:1.1:1.0-port0 -> ../../ttyUSB0 > > lrwxrwxrwx 1 root root 13 Jun 2 15:28 pci-0000:00:1d.0-usb-0:1.1:1.1-port0 -> ../../ttyUSB1 > > Ok, at least that matches what you found in schematics about this being > the ECI (and thus first) port. > > I just verified break signalling on the first port of my CP2105 using a > logic analyser and everything seems to work as expected. > > There's also no mention of any issue with break in the errata. > > Could you check which firmware revision you have by enabling debugging > and reconnecting the device? > > For example: > > echo func cp210x_get_fw_version +p > /sys/kernel/debug/dynamic_debug/control I couldn't get that to work (didn't try too hard), so I just stuck in a dev_info(): [ 4.253869] usb 2-1.2: new full-speed USB device number 3 using ehci-pci [ 4.342570] usb 2-1.2: New USB device found, idVendor=10c4, idProduct=ea70, bcdDevice= 1.00 [ 4.350939] usb 2-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=5 [ 4.358259] usb 2-1.2: Product: CP2105 Dual USB to UART Bridge Controller [ 4.365052] usb 2-1.2: Manufacturer: Silicon Labs [ 4.369765] usb 2-1.2: SerialNumber: 01070456 [ 4.374925] cp210x 2-1.2:1.0: cp210x converter detected [ 4.381086] cp210x 2-1.2:1.0: cp210x_get_fw_version - 1.18.1 [ 4.386915] usb 2-1.2: cp210x converter now attached to ttyUSB0 [ 4.393529] cp210x 2-1.2:1.1: cp210x converter detected [ 4.399835] cp210x 2-1.2:1.1: cp210x_get_fw_version - 1.18.1 [ 4.405657] usb 2-1.2: cp210x converter now attached to ttyUSB1 This is an embedded reference board, I guess there is some probability that this is just broken on this board, though I'm not quite sure how. Thanks for working on this. -corey
